| As a kind of novel microgrid power supply form,hybrid AC/DC microgrid combining the benefits of AC and DC microgrids will be one of the most important section in the future smart grid.A stable operation of hybrid AC / DC microgrid is the basic control objective.To improve the reliability and stability of hybrid AC / DC microgrid,it is necessary to develop an efficient and reasonable control strategy for the AC/DC sub-microgrids.Besides,with the growing demand for more reliable power supply and higher power quality,DC bus voltage ripple has drawn increasing attentions and it is of great practical significance to study a flexible and efficient DC bus voltage ripple suppression method.Firstly,the configuration and operation control strategy of the hybrid AC/DC microgrids are introduced,and then the mathematical models and control strategy of the DC-DC converter and DC-AC converter are analyzed.Secondly,a unified control strategy applied to the bidirecitional DC-AC interfacing converters in hybrid AC/DC microgrids is proposed,of which the design method is analyzed and the effectiveness is verified by simulations and experimentions.Then,the reasons of DC bus voltage 2nd harmonic ripple in hybrid AC/DC microgird are analyzed and a DC bus voltage ripple suppression method applied to the DC active power filter has been proposed the simulation and experimental results show that DC active power filters can realize the functions of ‘plug and play' and parallel operation.The proposed control strategy is also approved effectively by simulation models.In the end,the experimental structures are built in hybrid AC/DC microgrid experiment platform,verifying the effectiveness of the proposed control methods. |
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